To improve the design or quality of automotive decoration or the like, the decorative parts of an automobile (i.e. the console-box, the instrument-panel and the arm-rest or the like) of which decorations are added onto the resin-compact surface of the parts-material are nowadays practically used. An example of the wide variety of decorative patterns used on the surface of said parts-material is the hairline-pattern. The hairline-pattern is one of which a number of hair-like lines are streamed in a single direction onto the surface of the parts-material. Generally, such a pattern is formed by a hairline-process of which a hairline-processing machine physically scratches very fine grooves onto the surface of the parts-material. Originally, the hairline process was done on shiny silvery-metallic materials such as aluminum, stainless steel or the like. It is recognized that doing such a process exaggerates the metallic texture of such silvery-metallic materials, thus causing a muted design.
As a decorating method of which a hairline pattern is provided onto the surface of said parts-material, a method using a decorating-sheet for example was conventionally suggested (see Patent Document 1). By the method shown in Patent Document 1, a decorating-sheet having a transfer layer of the hairline-pattern is initially prepared by using processing equipment incorporating sand paper and metallic brushes or the like. Tucking the decorating-sheet inside the metallic-mold and then molding it by injection produces a resin-compact of which the transfer-layer of the hairline-pattern is transferred onto the parts-material surface.
Another method is one by which hairline-pattern printing-layers, accumulated on the base material film, is hairline-like embossed, thus transferring the hairline pattern onto the surface of the resin compact, as initially suggested (see Patent Document 2). Another method is one by which the coating-film that was formed on the surface of the parts-material is removed by sand paper or by a metallic brush or the like, which method was also suggested (see Patent Document 3).
Recently, another method was used by which a group of laser-processed grooves made of multiple laser-processed grooves is formed on the surface of the coating-film of the parts-material by a laser-drawing process, thus directly adding the hairline-patterns onto the coating-film (see FIG. 1 of Patent Document 4).